Field of the Invention
The present invention relates to an image pickup apparatus, and more particularly, to an image pickup apparatus having a function of outputting a partially read-out taken image.
Description of the Related Art
In production lines of factories, image pickup apparatus for image input have been used instead of visual inspection by an inspector. Those image pickup apparatus are also called machine vision cameras, which are used for inspecting various components and products together with a computer or a digital input/output apparatus. In recent years, in order to improve the inspection accuracy, an image pickup apparatus including ten-million or more pixels has been used.
When such an image pickup apparatus is used to image a subject and read out signals from all of the pixels in the pixel arrays, the number of pixels is large, and hence a long period of time is necessary to read out the signals from the pixel arrays. This reduces the number of images to be taken per second. Further, the amount of data of the taken image to be output to an external device increases, and hence the frame rate decreases. As described above, in the machine vision camera, the total period of time for readout changes depending on the number of pixels for image pickup, and the frame rate changes depending on the number of pixels to be transmitted to a portion external to the image pickup apparatus as an image.
In view of this, in Japanese Patent Application Laid-Open No. H09-214836, there is proposed a technology of reducing a time period to read out signals from pixel arrays by performing so-called thinning-readout of specifying a part of the pixel arrays as an interest area and reading out only the interest area. According to this technology, the number or images to be taken per second increases. Further, the amount of data of the taken image to be output to the external device reduces to increase the frame rate. Such thinning-readout can be set dynamically, and the frame rate changes depending on the number of pixels that are read out and the amount of data to be output to the external device.
For example, in Japanese Patent Application Laid-Open No. H09-214836, there is disclosed a technique of operating the readout of an image pickup element and causing a display device to simultaneously display all of the pixels and partially enlarged pixels so as to facilitate adjustment of the angle of view before image pickup.
However, the related art disclosed in Japanese Patent Application Laid-Open No. H09-214836 described above cannot respond to a case where multiple interest areas are present. Further, the relative positional relationship of the interest area with respect to the entire pixel image is not clear, and hence it is difficult to set the interest area.